Isoparaffin-olefin alkylation

ABSTRACT

A novel alkylation catalyst is described which is used in processes for alkylating olefin hydrocarbons with isoparaffin hydrocarbons to produce high octane alkylate products suitable for use as a blending component of gasoline motor fuel. The novel catalyst comprises a mixture of a hydrogen halide and a sulfone. The novel alkylation catalyst is utilized in a novel process for alkylating olefin hydrocarbons with isoparaffin hydrocarbons.

This is a division of application Ser. No. 08/075,427, filed Jun. 14,1993 now abandoned, which is a continuation-in-part of application Ser.No. 07/877,338, filed May 1, 1992 now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to a hydrocarbon conversion process and acatalyst composition to be utilized in said hydrocarbon conversionprocess. More particularly, the invention relates to an improvedalkylation process for the production of an alkylate product bycontacting hydrocarbon with a novel catalyst composition.

The use of catalytic alkylation processes to produce branchedhydrocarbons having properties that are suitable for use as gasolineblending components is well known in the art. Generally, the alkylationof olefins by saturated hydrocarbons, such as isoparaffins, isaccomplished by contacting the reactants with an acid catalyst to form areaction mixture, settling said mixture to separate the catalyst fromthe hydrocarbons, and further separating the hydrocarbons, for example,by fractionation, to recover the alkylation reaction product. Normally,the alkylation reaction product is referred to as “alkylate”, and itpreferably contains hydrocarbons having seven to nine carbon atoms. Inorder to have the highest quality gasoline blending stock, it ispreferred that the hydrocarbons formed in the alkylation process behighly branched.

One of the more desirable alkylation catalysts is hydrofluoric acid,however, the use of hydrofluoric acid as an alkylation catalyst hascertain drawbacks. One of the primary problems with the use ofhydrofluoric acid as an alkylation catalyst is that it is a highlycorrosive substance and it is toxic to human beings. The toxicity ofhydrofluoric acid to human beings is further complicated by the factthat anhydrous hydrofluoric acid is typically a gas at normalatmospheric conditions of one atmosphere of pressure and 70° F. It ispossible for the vapor pressure of hydrofluoric acid at standardatmospheric conditions to create certain safety concerns when it isexposed to the atmosphere. These safety concerns are created by the easewith which hydrofluoric acid is vaporized and released into theatmosphere.

In spite of the potential problems with human toxicity and the corrosivecharacteristics of hydrofluoric acid, industry has in the pastdetermined that the benefits from the use of hydrofluoric acid as analkylation catalyst outweigh the potential problems. For instance,hydrofluoric acid is an extremely effective alkylation catalyst in thatit permits the reaction of olefins by isoparaffins at low processpressures and process temperatures. HF is particularly suited for use asa catalyst in the alkylation of butylenes and, in the case of thealkylation of propylene and amylenes, HF has been used as an effectivecatalyst whereas other alkylation catalysts, such as sulfuric acid, havebeen found to be not as effective in such alkylation services.Additionally, the alkylate formed from a hydrofluoric acid alkylationprocess is of a very high quality having such desirable properties asbeing a mixture of highly branched hydrocarbon compounds that provide ahigh octane motor fuel. Generally, it has been found that the alkylateproduced by a hydrofluoric acid alkylation process has a higher octanevalue than that produced by typical sulfuric acid alkylation processes.Thus, it would be desirable to use an alkylation catalyst that has thedesirable features of hydrofluoric acid catalyst but without having itshigh vapor pressure.

SUMMARY OF THE INVENTION

It is, therefore, an object of this invention to provide a novelalkylation catalyst having the desirable property of yielding a highquality alkylate when utilized in the alkylation of olefins withparaffins but having a lower vapor pressure than that of hydrofluoricacid.

A further object of this invention is to provide a process for thealkylation of olefins with paraffins in the presence of an alkylationcatalyst having the desirable property of having a reduced vaporpressure but which produces a high quality alkylate product.

Thus, the process of the present invention relates to the alkylation ofa hydrocarbon mixture comprising olefins and paraffins with a catalystcomposition comprising the components of a hydrogen halide and asulfone, wherein the sulfone component is present in said catalystcomposition in an amount less than about 50 weight percent of the totalweight of said composition and wherein the weight ratio of hydrogenhalide to sulfone is at least 1:1.

The composition of the present invention comprises the components of ahydrogen halide and a sulfone, wherein said sulfone component is presentin said composition in an amount less than about 50 weight percent ofthe total weight of said composition and wherein the weight ratio ofhydrogen halide to sulfone is at least 1:1.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the invention will be apparent from thedetailed description of the invention, the appended claims and thedrawing in which:

FIG. 1 is a graphical diagram illustrating at a given temperature thechange in vapor pressure of the novel hydrogen fluoride and sulfolanecatalyst mixture as a function of the weight percent sulfolane in thecatalyst mixture.

FIG. 2 is a graphical diagram comparing the selectivity of the processof alkylating butylenes by isobutane when the novel hydrogen fluorideand sulfolane catalyst mixture is utilized toward the production oftrimethylpentane as a function of weight percent sulfolane in thecatalyst mixture.

FIG. 3 is a graphical diagram comparing the ratio of trimethylpentane todimethylhexane contained in the product of the alkylation process thatuses the novel hydrogen fluoride and sulfolane catalyst mixture in thealkylation of butylenes by isobutane as a function of the weight percentsulfolane in the catalyst mixture.

FIG. 4 is a graphical diagram comparing the octane of the product of thealkylation process that uses the novel hydrogen fluoride and sulfolanecatalyst mixture in the alkylation of butylenes by isobutane as afunction of the weight percent sulfolane in the catalyst mixture.

FIG. 5 is a graphical diagram comprising the calculated octane value ofthe product of the alkylation process, in which a representativerefinery feed is processed, that uses the novel hydrogen fluoride andsulfolane catalyst mixture as a function of the weight percent sulfolanein the catalyst mixture.

FIG. 6 is a graphical diagram comparing the selectivity of thealkylation process, in which a representative refinery feed is processedand the novel hydrogen fluoride and sulfolane catalyst mixture isutilized, toward the production of trimethylpentanes as a function ofweight percent sulfolane in the catalyst mixture.

DETAILED DESCRIPTION OF THE INVENTION

The novel composition of the present invention is suitable for use as analkylation catalyst and can comprise, consist of, or consist essentiallyof a hydrogen halide component and a sulfone component. The term“consisting essentially of” as used herein when referring to thealkylation catalyst composition is intended to mean that the compositioncontains nothing, in addition to the requisite amount of hydrogen halidecomponent and sulfone component, which would have a substantial adverseeffect on the ability of the composition to act as a catalyst in analkylation reaction.

The hydrogen halide component of the catalyst composition or catalystmixture can be selected from the group of compounds consisting ofhydrogen fluoride (HF), hydrogen chloride (HCl), hydrogen bromide (HBr),and mixtures of two or more thereof. The preferred hydrogen halidecomponent, however, is hydrogen fluoride, which can be utilized in thecatalyst composition in anhydrous form, but, generally, the hydrogenfluoride component utilized can have a small amount of water. The amountof water present in the hydrogen fluoride and sulfolane mixture in noevent can be more than about 30 weight percent of the total weight ofthe hydrogen fluoride component, which includes the water, andpreferably, the amount of water present in the hydrogen fluoridecomponent is less than about 10 weight percent. Most preferably, theamount of water present in the hydrogen fluoride component is less than5 weight percent. When referring herein to the hydrogen halidecomponent, or more specifically to the hydrogen fluoride component, ofthe catalyst composition of the invention, it should be understood thatthese terms mean either the hydrogen halide component as an anhydrousmixture or a mixture that includes water. The references herein toweight percent water contained in the hydrogen halide component meansthe ratio of the weight of water to the sum weight of the water andhydrogen halide multiplied by a factor of 100 to place the weight ratioin terms of percent.

The sulfone component is an important and critical component of thecatalyst composition because of the several functions it serves andbecause of the unexpected physical properties that it imparts to thecatalyst composition. One important function of the presence of thesulfone component in the composition is its vapor pressure depressanteffect upon the overall catalyst composition. It is an essential aspectof this invention for the sulfone component to be soluble in thehydrogen halide component and for the sulfone component to beessentially immiscible with olefin and paraffin hydrocarbons so as topermit easy separation of the hydrocarbons from the catalystcomposition. Also, it is essential for the presence of the sulfonecomponent to have a minimal impact upon an alkylation reactionselectivity and activity.

Generally, those skilled in the art of hydrogen fluoride catalyzedolefin alkylation processing have known that to obtain the highestquality of alkylate from the aforementioned olefin alkylation process,it is essential for the hydrogen fluoride catalyst to be as free fromcontaminating compounds as is feasible. It is generally known that smallamounts of other compounds contained in the hydrogen fluoride catalystof an olefin alkylation process can have detrimental effects uponproduct alkylate quality by negatively affecting the selectivity of thealkylation reaction toward the production of more desirable end-product,such as, for example, trimethylpentanes (TMP) in the case of thealkylation of butylenes by isobutane. It is further known to thoseskilled in the art that small amounts of components contained in ahydrogen fluoride alkylation catalyst can have a negative impact uponits activity toward the alkylation of olefins. Based upon the knowneffects of hydrogen fluoride catalyst contaminants upon the activity andselectivity of the alkylation process toward the production of highquality alkylate, one skilled in the art would expect that the additionof small to large amounts of a sulfone compound to a hydrogen fluoridecatalyst would have an enormously detrimental effect upon its catalyticperformance. However, it has been discovered that the presence of smallquantities of a sulfone compound in combination with hydrogen fluoridewill have little negative impact on the performance of the resultantmixture as an alkylation catalyst, but, it is further unexpected thatinstead of having a detrimental impact upon the catalytic performance, asmall concentration in an amount less than about 30 weight percent of asulfone component in combination with the hydrogen fluoride can enhancethe performance of the resultant composition as an alkylation processcatalyst. Therefore, to take advantage of the vapor pressure depressanteffects of the sulfone compound, it is desirable to utilize the sulfonein the catalyst mixture in an amount in the range of from about 2.5weight percent to about 50 weight percent. A concentration of thesulfone in the catalyst mixture exceeding 50 weight percent has such asignificantly negative impact upon alkylate quality when the compositionis utilized as an alkylation reaction catalyst that the compositionbecomes ineffective as a catalyst. Thus, 50 weight percent sulfone inthe catalyst mixture becomes a critical upper limit for the sulfonecompound. In the situation where both vapor pressure depression andimproved catalytic activity and selectivity are desired, the compositionthat works best in the alkylation of olefins has less than 30 weightpercent sulfone. To achieve optimal benefits from the catalystcomposition, the preferred catalyst mixture should contain the sulfonecomponent in the range of from about 5 weight percent to about 30 weightpercent and, more preferably, the sulfone concentration shall range from10 to 25 weight percent.

In addition to the above-described concentration ranges and limitationsfor the sulfone component of the catalyst mixture, it is essential, ifnot critical, for the weight ratio of the hydrogen halide to sulfone inthe catalyst mixture to be at least about 1:1. The reason for such aminimum weight ratio of hydrogen halide to sulfone in the catalystmixture is that the ratio of less than 1:1 has such a negative impactupon the alkylate quality when the catalyst composition is utilized asan alkylation reaction catalyst that composition becomes commerciallyineffective as a catalyst. Therefore, a 1:1 weight ratio of hydrogenhalide to sulfone in the catalyst mixture becomes a critical lower limitfor this ratio.

The sulfones suitable for use in this invention are the sulfones of thegeneral formulaR—SO₂—R′wherein R and R′ are monovalent hydrocarbon alkyl or aryl substituents,each containing from 1 to 8 carbon atoms. Examples of such substituentsinclude dimethylsulfone, di n-propylsulfone, diphenylsulfone,ethylmethylsulfone and the alicyclic sulfones wherein the SO₂ group isbonded to a hydrocarbon ring. In such a case, R and R′ are formingtogether a branched or unbranched hydrocarbon divalent moiety preferablycontaining from 3 to 12 carbon atoms. Among the latter,tetramethylenesulfone or sulfolane, 3-methylsulfolane and2,4-dimethylsulfolane are more particularly suitable since they offerthe advantage of being liquid at process operating conditions of concernherein. These sulfones may also have substituents, particularly one ormore halogen atoms, such as for example, chloromethylethylsulfone. Thesesulfones may advantageously be used in the form of mixtures.

This novel alkylation catalyst composition solves many of the problemsthat herebefore have been encountered in typical alkylation processesthat use hydrofluoric acid as an alkylation catalyst. For instance, thisnovel catalyst composition has a significantly lower vapor pressure thanthat of the standard hydrofluoric acid alkylation catalyst. Theadvantage of using an alkylation catalyst having a much lower vaporpressure than that of hydrofluoric acid is that a lesser amount of theacid catalyst will vaporize and enter into the atmosphere in cases wherethe catalyst is exposed to the atmosphere. In particular, when making acomparison between the novel catalyst composition and hydrofluoric acid,one notices a significant difference in the vapor pressures of the twocatalysts. The effect of the presence of sulfolane mixed with hydrogenfluoride is illustrated in the vapor pressure plot of FIG. 1. Sincehydrofluoric acid has a substantial vapor pressure at typicalatmospheric or ambient conditions, it is often in a vapor state at suchconditions, and this vapor pressure makes it a possibly lesscontrollable compound in cases where it is exposed to the environment.

The novel catalyst composition as described herein, solves many of theproblems associated with the use of hydrofluoric acid as a catalystsince it provides the benefit of having a lower vapor pressure atambient conditions than that of hydrofluoric acid. But, in addition tothe benefit of having a lower vapor pressure at ambient conditions, thenovel catalyst composition further can be utilized in typical alkylationprocesses to provide practical reaction rates at low operating pressuresand low operating temperatures to produce a high quality alkylateproduct which is suitable for use as a blending component of gasolinemotor fuel. A further benefit from the novel catalyst composition isthat it is easier to handle commercially than hydrofluoric acid.

The benefits from the use of a hydrogen fluoride and sulfone catalystmixture is also illustrated in FIGS. 2, 3 and 4 in which is shown thealkylate product quality that results from utilizing the novel hydrogenfluoride and sulfone co-mixture to catalyze the reaction of mono-olefinhydrocarbons by isoparaffins. As can be seen from FIG. 2, the totalamount of the more desirable alkylate product of trimethylpentaneproduced in the alkylation reaction of butylenes with isobutaneincreases with increases in the amount of sulfolane present in thealkylation catalyst mixture up to an optimum range of about 10 weightpercent sulfolane to about 25 weight percent sulfolane. Also, it isshown in FIG. 2 that there is a maximum amount of sulfolane present inthe catalyst mixture at which point the alkylate quality becomes soundesirable that the hydrogen fluoride and sulfolane mixture becomesineffective as a catalyst. Based on the data presented herein and inFIGS. 2, 3 and 4, it is believed that the critical upper limit for theamount of sulfolane contained in the hydrofluoride and sulfolanecatalyst mixture is about 50 weight percent.

Alkylation processes contemplated in the present invention are thoseliquid phase processes wherein mono-olefin hydrocarbons such aspropylene, butylenes, pentylenes, hexylenes, heptylenes, octylenes andthe like are alkylated by isoparaffin hydrocarbons such as isobutane,isopentane, isohexane, isoheptane, isooctane and the like for productionof high octane alkylate hydrocarbons boiling in the gasoline range andwhich are suitable for use in gasoline motor fuel. Preferably, isobutaneis selected as the isoparaffin reactant and the olefin reactant isselected from propylene, butylenes, pentylenes and mixtures thereof forproduction of an alkylate hydrocarbon product comprising a major portionof highly branched, high octane value aliphatic hydrocarbons having atleast seven carbon atoms and less than ten carbon atoms.

In order to improve selectivity of the alkylation reaction toward theproduction of the desirable highly branched aliphatic hydrocarbonshaving seven or more carbon atoms, a substantial stoichiometric excessof isoparaffin hydrocarbon is desirable in the reaction zone. Molarratios of isoparaffin hydrocarbon to olefin hydrocarbon of from about2:1 to about 25:1 are contemplated in the present invention. Preferably,the molar ratio of isoparaffin-to-olefin will range from about 5 toabout 20; and, most preferably, it shall range from 8 to 15. It isemphasized, however, that the above recited ranges for the molar ratioof isoparaffin-to-olefin are those which have been found to becommercially practical operating ranges; but, generally, the greater theisoparaffin-to-olefin ratio in an alkylation reaction, the better theresultant alkylate quality.

Isoparaffin and olefin reactant hydrocarbons normally employed incommercial alkylation processes are derived from refinery processstreams and usually contain small amounts of impurities such as normalbutane, propane, ethane and the like. Such impurities are undesirable inlarge concentrations as they dilute reactants in the reaction zone, thusdecreasing reactor capacity available for the desired reactants andinterfering with good contact of isoparaffin with olefin reactants.Additionally, in continuous alkylation processes wherein excessisoparaffin hydrocarbon is recovered from an alkylation reactioneffluent and recycled for contact with additional olefin hydrocarbon,such nonreactive normal paraffin impurities tend to accumulate in thealkylation system. Consequently, process charge streams and/or recyclestreams which contain substantial amounts of normal paraffin impuritiesare usually fractionated to remove such impurities and maintain theirconcentration at a low level, preferably less than about 5 volumepercent, in the alkylation process.

Alkylation reaction temperatures within the contemplation of the presentinvention are in the range of from about 0° F. to about 150° F. Lowertemperatures favor alkylation reaction of isoparaffin with olefin overcompeting olefin side reactions such as polymerization. However, overallreaction rates decrease with decreasing temperatures. Temperatureswithin the given range, and preferably in the range from about 30° F. toabout 130° F., provide good selectivity for alkylation of isoparaffinwith olefin at commercially attractive reaction rates. Most preferably,however, the alkylation temperature should range from 50° F. to 100° F.

Reaction pressures contemplated in the present invention may range frompressures sufficient to maintain reactants in the liquid phase to aboutfifteen (15) atmospheres of pressure. Reactant hydrocarbons may benormally gaseous at alkylation reaction temperatures, thus reactionpressures in the range of from about 40 pounds gauge pressure per squareinch (psig) to about 160 psig are preferred. With all reactants in theliquid phase, increased pressure has no significant effect upon thealkylation reaction.

Contact times for hydrocarbon reactants in an alkylation reaction zone,in the presence of the alkylation catalyst of the present inventiongenerally should be sufficient to provide for essentially completeconversion of olefin reactant in the alkylation zone. Preferably, thecontact time is in the range from about 0.05 minute to about 60 minutes.In the alkylation process of the present invention, employingisoparaffin-to-olefin molar ratios in the range of about 2:1 to about25:1, wherein the alkylation reaction mixture comprises about 40-90volume percent catalyst phase and about 60-10 volume percent hydrocarbonphase, and wherein good contact of olefin with isoparaffin is maintainedin the reaction zone, essentially complete conversion of olefin may beobtained at olefin space velocities in the range of about 0.1 to about200 volumes olefin per hour per volume catalyst (v/v/hr.). Optimum spacevelocities will depend upon the type of isoparaffin and olefin reactantsutilized, the particular compositions of alkylation catalyst, and thealkylation reaction conditions. Consequently, the preferred contacttimes are sufficient for providing an olefin space velocity in the rangeof about 0.1 to about 200 (v/v/hr.) and allowing essentially completeconversion of olefin reactant in the alkylation zone.

The process may be carried out either as a batch or continuous type ofoperation, although it is preferred for economic reasons to carry outthe process continuously. It has been generally established that inalkylation processes, the more intimate the contact between thefeedstock and the catalyst the better the quality of alkylate productobtained. With this in mind, the present process, when operated as abatch operation, is characterized by the use of vigorous mechanicalstirring or shaking of the reactants and catalyst.

In continuous operations, in one embodiment, reactants may be maintainedat sufficient pressures and temperatures to maintain them substantiallyin the liquid phase and then continuously forced through dispersiondevices into the reaction zone. The dispersion devices can be jets,nozzles, porous thimbles and the like. The reactants are subsequentlymixed with the catalyst by conventional mixing means such as mechanicalagitators or turbulence of the flow system. After a sufficient time, theproduct can then be continuously separated from the catalyst andwithdrawn from the reaction system while the partially spent catalyst isrecycled to the reactor. If desired, a portion of the catalyst can becontinuously regenerated or reactivated by any suitable treatment andreturned to the alkylation reactor.

The following examples demonstrate the advantages of the presentinvention. These examples are by way of illustration only, and are notintended as limitations upon the invention as set out in the appendedclaims.

EXAMPLE I

This example describes the experimental method used to determine thevapor pressure of various hydrogen fluoride and sulfolane mixtures andto present vapor pressure data for such mixtures demonstrating theeffectiveness of sulfolane as a vapor pressure depressant.

A 100 mL monel bomb was dried and evacuated, followed by the addition ofa prescribed amount of anhydrous hydrogen fluoride. A specific amount ofsulfolane was then added to the bomb. Once the bomb achieved the desiredtemperature, the pressure within the bomb was recorded. The vaporpressure was assumed to be that of HF vapor alone (sulfolane has aboiling point of 283° C.). FIG. 1 presents a portion of the vaporpressure data obtained by this experimental method and illustrates thechange in vapor pressure of the novel hydrogen fluoride and sulfolanecatalyst mixture as a function of the weight percent sulfolane in thecatalyst mixture.

EXAMPLE II

This example describes the method which utilizes batch reactions to testthe feasibility of using a hydrogen fluoride and sulfolane mixture as acatalyst for the alkylation of mono-olefins by isoparaffins. Data arepresented to demonstrate the unexpectedly improved properties of thealkylate product from such a catalytic process and to demonstrate thatfor certain concentration ranges the catalyst mixture unexpectedlyprovides a good quality alkylate.

HF/sulfolane mixtures were evaluated for alkylation performance in batchreactions at 90° F. In a typical trial, the desired amount of sulfolanewas added to a 300 mL monel autoclave under a blanket of nitrogen.Anhydrous HF was then introduced into the autoclave and heated to 90° F.with stirring at 500 RPM. The stirring was then increased to 2500 RPM,and an 8.5:1 isobutane:2-butenes mixture was added with nitrogenbackpressure at a rate of 100 mL/min. at a pressure of 150-200 psig.After 5 minutes, the stirring was stopped, followed by the transfer ofthe reactor contents to a Jerguson gauge for phase separation. Thehydrocarbon product was then characterized by gas chromatography.

The data presented in Table I were obtained by using the experimentalmethod described in this Example II. FIGS. 2 and 3 are graphicalrepresentations of this data. FIG. 2 compares the selectivity of thealkylation process toward the production of the highly desirabletrimethylpentanes as a function of weight percent sulfolane in thecatalyst mixture. FIG. 3 compares the ratio of trimethylpentanes todimethylhexanes contained in the alkylation product as a function of theweight percent sulfolane in the catalyst mixture.

TABLE I Batch Results, Anhydrous HF/Sulfolane Test Samples No. 1 No. 2No. 3 No. 4 No. 5 No. 6 mL sulfolane 0.00 13.00 28.00 38.00 50.00 50.00mL HF 100.00 93.50 86.00 81.00 75.00 50.00 mL Feed 100.00 93.50 86.0081.00 75.00 100.00 wt. % sulfolane 0.00 15.09 29.39 37.49 46.02 56.11 %TMP 65.40 71.28 67.29 57.14 52.21 20.45 % DMH 9.63 9.02 10.52 11.9012.28 1.58 TMP:DMH 6.79 7.90 6.40 4.80 4.25 12.97 C9+ 5.81 10.56 10.9816.49 18.96 0.28 Organic fluorides 0.00 0.00 0.00 0.00 0.00 69.74

EXAMPLE III

This example describes the steady state evaluation method for testingthe feasibility of using a hydrogen fluoride and sulfolane mixture as acatalyst for the alkylation of mono-olefins by isoparaffins. Data arepresented to demonstrate that for certain concentration ranges thecatalyst mixture unexpectedly provides a good quality alkylate.

A reactor was constructed to enable steady state evaluation ofHF/sulfolane alkylation catalysts using a 300 mL monel autoclave. A 10:1isobutane:2-butenes feed was introduced into the autoclave with stirringat 2000 RPM at a rate of 600 mL/hour. The reactor effluent flowed into amonel Jerguson gauge for phase separation. The hydrocarbon phase waspassed through alumina and collected, while the acid phase wasrecirculated to the reactor. Alkylate was evaluated by gaschromatography and by research and motor octane tests performed on testengines.

The data presented in Table II were obtained by using the experimentalmethod described in this Example III. FIG. 4 is a graphicalrepresentation of some of the data provided in Table II and compares theoctane of the alkylate product as a function of the weight percentsulfolane in the catalyst mixture. As is evident from the data presentedin Table II, the alkylate quality degenerates at the point where thecatalyst has a weight ratio of hydrogen fluoride to sulfolane of lessthan 1:1. This deterioration is demonstrated by that data presentedwhich depicts alkylate quality measures such as the concentration of C₈compounds, the ratio of TMP to DMH, the concentration of C₉+compoundsand the octane of the alkylate. As is shown in Table II, theconcentration of C₈ compounds and the ratio of TMP to DMH begin tosignificantly decline when the alkylation catalyst has a ratio ofhydrogen fluoride to sulfolane of less than 1:1. Also, the concentrationof undesirable C₉+compounds in the alkylate begins to significantlyincrease when a catalyst mixture having a ratio of hydrogen fluoride tosulfone is less than 1:1.

TABLE II 70/30 HF/ 60/40 HF/ 50/50 HF/ 40/60 HF/ 100 % HF sulfolanesulfolane sulfolane sulfolane C8 93.5 81.1 82.2 56.9 26.95 TMP 86.3 70.570.4 46.1 22.26 DMH 7.1 10.6 11.7 10.6 4.54 TMP/DMH 12.1 6.6 6.0 4.44.90 C9+ 3.4 3.9 8.1 23.1 36.32 R + M/2 97.0 95.5 94.9 93.7 NA

EXAMPLE IV

This example describes the steady state evaluation method for testingthe feasibility of using a hydrogen fluoride and sulfolane mixture as acatalyst for the alkylation of a typical refinery feed mixture ofmono-olefins and isoparaffins (BB Feed). Data are presented todemonstrate that for certain concentration ranges the catalyst mixtureunexpectedly provides a good quality alkylate.

A reactor was constructed to enable steady state evaluation ofHF/sulfolane alkylation catalysts using a 300 mL monel autoclave. Thefeed mixture of olefins and paraffins presented in Table III wasintroduced into the autoclave with stirring at 2000 RPM at a rate of 600mL/hour. The reactor effluent flowed into a monel Jerguson gauge forphase separation. The hydrocarbon phase was passed through alumina andcollected, while the acid phase was recirculated to the reactor.Alkylate was evaluated by gas chromatography and the octane values(R+M/2) were calculated using the method for computing alkylate octanedescribed in the publication authored by T. Hutson, Jr. and R. S. Loganin Hydrocarbon Processing, September 1975, pages 107-110. This publishedarticle is incorporated herein by reference.

TABLE III BB Feed Hydrocarbons Propylene 0.000 Propane 0.569 Isobutane88.027 1-butene 2.818 Isobutylene 0.000 1,3-butadiene 0.000 n-butane3.505 trans-2-butene 1.716 cis-2-butene 1.236 Isopentane 1.008 n-pentane0.728 C₅ olefins 0.393 100.000 Oxygenates Acetone 29 ppm Dimethyl ether10 ppm MTBE  1 ppm

The data presented in Table IV was obtained by using the experimentalmethod described in this Example IV. FIG. 5 is a graphicalrepresentation of some of the data provided in Table IV and compares thecalculated octane value of the alkylate product as a function of theweight percent sulfolane in the catalyst mixture. FIG. 6 compares theselectivity of the alkylation process, in which a BB feed is processed,toward the production of the highly desirable trimethylpentanes as afunction of weight percent sulfolane in the catalyst mixture.

TABLE IV 98/2 80/20 HF/ 65/35 HF/ 60/40 HF/ 100% HF HF/Water sulfolanesulfolane sulfolane Hours 17 Hrs 13 Hrs 20 Hrs 7 Hrs 11 Hrs C₈ 56.9 59.273.2 55.8 51.8 TMP 45.9 50.9 62.4 44.6 42.5 DMH 11.0 8.3 10.8 6.9 9.0TMP/DMH 4.2 6.1 5.8 6.5 4.7 C₉+ 3.9 2.6 4.2 11.4 6.8 (R + M)/2 92.5 94.295.7 92.1 91.7 (calculated)

While this invention has been described in terms of the presentlypreferred embodiment, reasonable variations and modifications arepossible by those skilled in the art. Such variations and modificationsare within the scope of the described invention and the appended claims.

1. A method of improving the quality of an alkylate product produced byan alkylation process including contacting a hydrocarbon mixturecontaining olefins and isoparaffins with a catalyst containing hydrogenfluoride to thereby produce said alkylate product, the method comprisingthe step of: incorporating a sulfone into said catalyst in an amountsuch that the octane of said alkylate product is higher than saidalkylate product produced when said catalyst contains no sulfone.
 2. Amethod as recited in claim 1 wherein said amount of said sulfoneincorporated into said catalyst is such that the weight ratio ofhydrogen fluoride to sulfone in said catalyst is at least about 1:1. 3.A method as recited in claim 2 wherein said amount of said sulfoneincorporated into said catalyst is such that the sulfone present in saidcatalyst is less than 30 weight percent.
 4. A method as recited in claim3 wherein said amount of said sulfone incorporated into said catalyst issuch that the sulfone present in said catalyst is in the range of from10 to 25 weight percent.
 5. A method as recited in claim 4 wherein saidsulfone is sulfolane.
 6. A method of improving the quality of analkylate product produced by an alkylation process including contactinga hydrocarbon mixture containing olefins and isoparaffins with acatalyst containing hydrogen fluoride to thereby produce said alkylateproduct, the method comprising the step of: incorporating a sulfone intosaid catalyst in an amount such that the ratio of trimethylpentane todimethylhexane in said alkylate product is higher than said alkylateproduct produced when said catalyst contains no sulfone.
 7. A method asrecited in claim 6 wherein said amount of said sulfone incorporated intosaid catalyst is such that the weight ratio of hydrogen fluoride tosulfone in said catalyst is at least about 1:1.
 8. A method as recitedin claim 7 wherein said amount of said sulfone incorporated into saidcatalyst is such that the sulfone present in said catalyst is less than30 weight percent.
 9. A method as recited in claim 8 wherein said amountof said sulfone incorporated into said catalyst is such that the sulfonepresent in said catalyst is in the range of from 10 to 25 weightpercent.
 10. A method as recited in claim 9 wherein said sulfone issulfolane.
 11. An improved alkylation process including contacting ahydrocarbon mixture containing olefins and isoparaffins with a catalystcontaining hydrogen fluoride to thereby produce an alkylate product,wherein the improvement comprises: incorporating a sulfone into saidcatalyst in an amount such that the sulfone present in said catalyst isless than 50 weight percent, whereby said alkylate product contains morehighly branched hydrocarbons than when said catalyst contains nosulfone.
 12. An alkylation process as recited in claim 11 wherein saidamount of sulfone incorporated into said catalyst is such that theweight ratio of hydrogen fluoride to sulfone in said catalyst is atleast about 1:1.
 13. An alkylation process as recited in claim 12wherein said amount of sulfone incorporated into said catalyst is suchthat the sulfone present in said catalyst is less than 30 weightpercent.
 14. A method as recited in claim 13 wherein said amount ofsulfone incorporated into said catalyst is such that the sulfone presentin said catalyst is in the range of from 10 to 25 weight percent.
 15. Amethod as recited in claim 14 wherein said sulfone is sulfolane.
 16. Amethod as recited in claim 1 wherein said amount of said sulfoneincorporated into said catalyst is such that the sulfone present in saidcatalyst is less than 50 weight percent.
 17. A method as recited inclaim 16 wherein said sulfone is sulfolane.
 18. A process comprisingcontacting under suitable alkylation reaction conditions a hydrocarbonmixture comprising olefins and paraffins with a catalyst compositioncomprising the components of a hydrogen halide, and a sulfone, whereinthe sulfone component is present in said catalyst composition in anamount less than about 50 weight percent of the total weight of saidcomposition, wherein the weight ratio of hydrogen halide to sulfone isat least about 1:1, and wherein said sulfone component is sulfolane. 19.A process as recited in claim 18 wherein said hydrogen halide componentis hydrogen fluoride.
 20. A process as recited in claim 19 wherein saidsulfone component is present in said catalyst composition in an amountin the range of from about 2.5 to about 50 weight percent of the totalweight of said composition.
 21. A process as recited in claim 19 whereinsaid sulfone component is present in said composition in an amount inthe range of from about 5 to about 35 weight percent of the total weightof said composition.
 22. A process as recited in claim 21 wherein saidsulfone component is present in said composition in an amount in therange of from about 10 to about 25 weight percent of the total weight ofsaid composition.
 23. A process as recited in claim 18 wherein thealkylation reaction temperature is in the range of from about 0° F. toabout 150° F. and the alkylation reaction pressure is in the range offrom about ambient pressure to about 15 atmospheres.
 24. A process asrecited in claim 18 wherein the molar ratio of paraffin to olefin insaid hydrocarbon mixture is in the range of from about 2 to 1 to about25 to
 1. 25. A process as recited in claim 18 wherein said olefins aremono-olefins having from 2 to 12 carbon atoms, and wherein saidparaffins are isoparaffins having from 4 to 8 carbon atoms.
 26. Aprocess comprising: introducing a hydrocarbon mixture comprising olefinsand paraffins into a reactor zone; and contacting said hydrocarbonmixture within said reactor zone, at alkylation reaction conditions,with a catalyst mixture formed from a hydrogen halide and a sulfone,wherein the sulfone is present in said catalyst mixture in an amountless than about 50 weight percent of the total weight of said catalystmixture, wherein the weight ratio of hydrogen halide to sulfone is atleast about 1:1, and wherein said sulfone component is sulfolane.
 27. Aprocess as recited in claim 26 wherein said hydrogen halide component ishydrogen fluoride.
 28. A process as recited in claim 27 wherein saidsulfone component is present in said catalyst composition in an amountin the range of from about 2.5 to about 50 weight percent of the totalweight of said composition.
 29. A process as recited in claim 27 whereinsaid sulfone component is present in said composition in an amount inthe range of from about 5 to about 35 weight percent of the total weightof said composition.
 30. A process as recited in claim 29 wherein saidsulfone component is present in said composition in an amount in therange of from about 10 to about 25 weight percent of the total weight ofsaid composition.
 31. A process as recited in claim 26 wherein thealkylation reaction temperature is in the range of from about 0° F. toabout 150° F. and the alkylation reaction pressure is in the range offrom about ambient pressure to about 15 atmospheres.
 32. A process asrecited in claim 26 wherein the molar ratio of paraffin to olefin insaid hydrocarbon mixture is in the range of from about 2 to 1 to about25 to
 1. 33. A process as recited in claim 26 wherein said olefins aremono-olefins having from 2 to 12 carbon atoms, and wherein saidparaffins are isoparaffins having from 4 to 8 carbon atoms.
 34. In analkylation process of the type wherein a hydrocarbon mixture includingolefins and isoparaffins is contacted with a hydrogen fluoride catalyst,the improvement comprising: utilizing sulfolane with said hydrogenfluoride catalyst in an amount less than about 50 weight percent of thetotal weight of said hydrogen fluoride catalyst and sulfolane and insuch an amount wherein the weight ratio of hydrogen fluoride in saidhydrogen fluoride catalyst to sulfolane is at least 1:1.
 35. A processcomprising contacting under suitable alkylation reaction conditions ahydrocarbon mixture comprising olefins and paraffins with a catalystcomposition consisting essentially of the components of a hydrogenhalide, and a sulfone, wherein said sulfone is present in said catalystcomposition in an amount less than about 50 weight percent of the totalweight of said catalyst composition, wherein the weight ratio of saidhydrogen halide to said sulfone is at least about 1:1, and wherein saidsulfone is sulfolane.
 36. A process as recited in claim 35 wherein saidhydrogen halide is hydrogen fluoride.
 37. A process as recited in claim36 wherein said sulfone is present in said catalyst composition in anamount in the range of from about 2.5 to about 50 weight percent of thetotal weight of said catalyst composition.
 38. A process as recited inclaim 36 wherein said sulfone is present in said catalyst composition inan amount in the range of from about 5 to about 35 weight percent of thetotal weight of said catalyst composition.
 39. A process as recited inclaim 36 wherein said sulfone is present in said catalyst composition inan amount in the range of from about 10 to about 25 weight percent ofthe total weight of said catalyst composition.
 40. A process as recitedin claim 39 wherein the alkylation reaction temperature is in the rangeof from about 0° F. to about 150° F. and the alkylation reactionpressure is in the range of from about ambient pressure to about 15atmospheres.
 41. A process as recited in claim 40 wherein the molarratio of paraffin to olefin in said hydrocarbon mixture is in the rangeof from about 2 to 1 to about 25 to
 1. 42. A process as recited in claim41 wherein said olefins are mono-olefins having from 2 to 12 carbonatoms, and wherein said paraffins are isoparaffins having from 4 to 8carbon atoms.
 43. A process as recited in claim 19 wherein said sulfonecomponent is present in said catalyst composition in an amount which isless than about 35 weight percent of the total weight of saidcomposition.
 44. A process as recited in claim 19 wherein the sulfonecomponent is present in said catalyst composition in an amount that isless than about 30 weight percent of the total weight of saidcomposition.
 45. A process as recited in claim 19 wherein said sulfonecomponent is present in said catalyst composition in an amount that isless than about 25 weight percent of the total weight of saidcomposition.
 46. A process as recited in claim 27 wherein said sulfonecomponent is present in said catalyst composition in an amount which isless than about 35 weight percent of the total weight of saidcomposition.
 47. A process as recited in claim 27 wherein the sulfonecomponent is present in said catalyst composition in an amount that isless than about 30 weight percent of the total weight of saidcomposition.
 48. A process as recited in claim 27 wherein said sulfonecomponent is present in said catalyst composition in an amount that isless than about 25 weight percent of the total weight of saidcomposition.
 49. A process as recited in claim 34 wherein said sulfolaneis present in said catalyst composition in an amount which is less thanabout 35 weight percent of the total weight of said composition.
 50. Aprocess as recited in claim 34 wherein the sulfolane is present in saidcatalyst composition in an amount that is less than about 30 weightpercent of the total weight of said composition.
 51. A process asrecited in claim 34 wherein said sulfolane is present in said catalystcomposition in an amount that is less than about 25 weight percent ofthe total weight of said composition.
 52. A process as recited in claim37 wherein said sulfone component is present in said catalystcomposition in an amount which is less than about 35 weight percent ofthe total weight of said composition.
 53. A process as recited in claim37 wherein the sulfone component is present in said catalyst compositionin an amount that is less than about 30 weight percent of the totalweight of said composition.
 54. A process as recited in claim 37 whereinsaid sulfone component is present in said catalyst composition in anamount that is less than about 25 weight percent of the total weight ofsaid composition.